Each piece of envelope material consists of a plane sheet, which is folded along a line, mainly a bending line, so that two envelope halves are created, which are folded against each other thus forming an envelope. The envelope material is provided with strings of glue so that the envelope halves, when they are folded against each other, will adhere to each other so that an enclosed envelope is obtained. It is usually sufficient to use three strings of glue as the fourth edge of the envelope formed makes up the mentioned bending line. Furthermore, the envelope material is provided with a see-through window. In this respect, a window opening is cut and covered by transparent foil, which is glued along the edges of the window opening. The strings of glue and the layer forming the window are arranged on the same side of the envelope material. The envelope materials are usually fed to an enveloping machine. The formed envelope, i.e. when the two halves of the envelope material lie against each other, is supplied with the contents with which the envelope is to be filled before the sealing of the envelope takes place. As enveloping machines operate at a very high speed, the individual envelope materials must be connected one after the other so that a long row of envelope materials is obtained. The envelope materials which are arranged one after the other form a band. In the enveloping machine, the individual envelope materials are separated from the band and folded so that two opposite halves are obtained.
The band with the envelope material must be supplied to the enveloping machine in the form of a unit, and it has been determined that it is easiest to shape the band so that a pile is obtained, i.e. the band is shaped zigzag and each zigzag unit consists of an envelope material.
By supplying a pile of envelope materials to the enveloping machine, the handling of the envelope materials becomes a little jerky. A better way of supplying envelope materials to an enveloping machine would be to have the envelope materials stored in the form of a roll. If a roll is to be used for storage, very large requirements will be made for the cylindrical shape of the roll, both as regards the speed of rotation of the roll and as regards the storage of the roll.